#include <iostream>
#include <ceres/ceres.h>

using ceres::AutoDiffCostFunction;
using ceres::CostFunction;
using ceres::Problem;
using ceres::Solver;
using ceres::Solve;

const int kNumObservations=67;
//观测值
const double data[]={
        0.000000e+00, 1.133898e+00,
        7.500000e-02, 1.334902e+00,
        1.500000e-01, 1.213546e+00,
        2.250000e-01, 1.252016e+00,
        3.000000e-01, 1.392265e+00,
        3.750000e-01, 1.314458e+00,
        4.500000e-01, 1.472541e+00,
        5.250000e-01, 1.536218e+00,
        6.000000e-01, 1.355679e+00,
        6.750000e-01, 1.463566e+00,
        7.500000e-01, 1.490201e+00,
        8.250000e-01, 1.658699e+00,
        9.000000e-01, 1.067574e+00,
        9.750000e-01, 1.464629e+00,
        1.050000e+00, 1.402653e+00,
        1.125000e+00, 1.713141e+00,
        1.200000e+00, 1.527021e+00,
        1.275000e+00, 1.702632e+00,
        1.350000e+00, 1.423899e+00,
        1.425000e+00, 1.543078e+00,
        1.500000e+00, 1.664015e+00,
        1.575000e+00, 1.732484e+00,
        1.650000e+00, 1.543296e+00,
        1.725000e+00, 1.959523e+00,
        1.800000e+00, 1.685132e+00,
        1.875000e+00, 1.951791e+00,
        1.950000e+00, 2.095346e+00,
        2.025000e+00, 2.361460e+00,
        2.100000e+00, 2.169119e+00,
        2.175000e+00, 2.061745e+00,
        2.250000e+00, 2.178641e+00,
        2.325000e+00, 2.104346e+00,
        2.400000e+00, 2.584470e+00,
        2.475000e+00, 1.914158e+00,
        2.550000e+00, 2.368375e+00,
        2.625000e+00, 2.686125e+00,
        2.700000e+00, 2.712395e+00,
        2.775000e+00, 2.499511e+00,
        2.850000e+00, 2.558897e+00,
        2.925000e+00, 2.309154e+00,
        3.000000e+00, 2.869503e+00,
        3.075000e+00, 3.116645e+00,
        3.150000e+00, 3.094907e+00,
        3.225000e+00, 2.471759e+00,
        3.300000e+00, 3.017131e+00,
        3.375000e+00, 3.232381e+00,
        3.450000e+00, 2.944596e+00,
        3.525000e+00, 3.385343e+00,
        3.600000e+00, 3.199826e+00,
        3.675000e+00, 3.423039e+00,
        3.750000e+00, 3.621552e+00,
        3.825000e+00, 3.559255e+00,
        3.900000e+00, 3.530713e+00,
        3.975000e+00, 3.561766e+00,
        4.050000e+00, 3.544574e+00,
        4.125000e+00, 3.867945e+00,
        4.200000e+00, 4.049776e+00,
        4.275000e+00, 3.885601e+00,
        4.350000e+00, 4.110505e+00,
        4.425000e+00, 4.345320e+00,
        4.500000e+00, 4.161241e+00,
        4.575000e+00, 4.363407e+00,
        4.650000e+00, 4.161576e+00,
        4.725000e+00, 4.619728e+00,
        4.800000e+00, 4.737410e+00,
        4.875000e+00, 4.727863e+00,
        4.950000e+00, 4.669206e+00,
};

//代价函数结构体
struct ExponetialResidual{
    ExponetialResidual(double x, double y):x_(x),y_(y) {}
    template <typename T> bool operator() (const T *const m, const T* const c, T* residual) const{
        residual[0]=y_-exp(m[0]*x_+c[0]);
        return true;
    }
private:
    const double x_;
    const double y_;
};

int main(int argc, char **argv)
{
    double m=0.0;
    double c=0.0;
    
    //构建寻优问题
    Problem problem;
    for(int i=0;i<kNumObservations; ++i){
        problem.AddResidualBlock(
            new AutoDiffCostFunction<ExponetialResidual, 1, 1, 1>(
                new ExponetialResidual(data[2*i],data[2*i+1])),
            NULL,
            &m,&c);
    }
    
    //配置并运行求解器
    Solver::Options options;
    options.max_num_iterations=25;
    options.linear_solver_type=ceres::DENSE_QR;
    options.minimizer_progress_to_stdout=true;
    
    Solver::Summary summary;
    Solve(options, &problem, &summary);
    std::cout<<summary.BriefReport()<<"/n";
    std::cout<<"Initial m: "<<0.0<<" c: "<<0.0<<"\n";
    std::cout<<"Final m: "<<m<<" c: "<<c<<" \n";
    return 0;
}
